1：SL的資料驗證和WPF的不同
首先，很遺憾，SL中不再存在ValidationRules，要在SL中綁定時驗證資料，并且顯示在UI，隻能依賴于NotifyOnValidationError=True, ValidatesOnExceptions=True這兩個屬性，如下：
》。
2：一般情況下的驗證
一般情況下，UI綁定資料類型的屬性，如在上圖中，綁定的就是Name和Age，它在UI的VIEWMODEL中，如下：
public class MainPageVM : INotifyPropertyChanged
{
public MainPageVM()
{
}
private string name = "luminji";
public string Name
{
get { return name; }
set
{
if (string.IsNullOrEmpty(value))
{
throw new Exception("姓名不能為空");
}
name = value;
OnPropertyChanged("Name");
}
}
private int age = 1;
public int Age
{
get { return age; }
set
{
if (value > 100)
{
throw new Exception("年齡必須小與100");
}
age = value;
OnPropertyChanged("Age");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler pceh = PropertyChanged;
if (pceh != null)
{
pceh(this, new PropertyChangedEventArgs(propertyName));
}
}
} 采用UI直接綁定VM的屬性，如果Age>100，則UI會提示出現輸入有誤。
3：綁定實體類型
不過，如果屬性很多，我們就會考慮綁定實體類型。如User，而這個實體類，是在伺服器端的，形如：
public class User
{
private string name = "luminji";
public string Name
{
get { return name; }
set
{
name = value;
}
}
private int age = 1;
public int Age
{
get { return age; }
set
{
age = value;
}
}
} 比如，我們使用的是Ria Service。Ria Service有可能是從DAL層擷取資料并開放接口給用戶端。我們都知道，用戶端的代碼都是自動生成的，自動生成的代碼在SL項目的Generated_Code目錄下的（SL項目名）.Web.g.cs檔案下。是以，最終User類型在用戶端的代理形式為：
/// <summary>
/// The 'User' entity class.
/// </summary>
[DataContract(Namespace="http://schemas.datacontract.org/2004/07/SilverlightApplication3.Web.Model")]
public sealed partial class User : Entity
{
private int _age;
private string _name;
#region Extensibility Method Definitions
/// <summary>
/// This method is invoked from the constructor once initialization is complete and
/// can be used for further object setup.
/// </summary>
partial void OnCreated();
partial void OnAgeChanging(int value);
partial void OnAgeChanged();
partial void OnNameChanging(string value);
partial void OnNameChanged();
#endregion
/// <summary>
/// Initializes a new instance of the <see cref="User"/> class.
/// </summary>
public User()
{
this.OnCreated();
}
/// <summary>
/// Gets or sets the 'Age' value.
/// </summary>
[DataMember()]
public int Age
{
get
{
return this._age;
}
set
{
if ((this._age != value))
{
this.OnAgeChanging(value);
this.RaiseDataMemberChanging("Age");
this.ValidateProperty("Age", value);
this._age = value;
this.RaiseDataMemberChanged("Age");
this.OnAgeChanged();
}
}
}
/// <summary>
/// Gets or sets the 'Name' value.
/// </summary>
[DataMember()]
[Editable(false, AllowInitialValue=true)]
[Key()]
[RoundtripOriginal()]
public string Name
{
get
{
return this._name;
}
set
{
if ((this._name != value))
{
this.OnNameChanging(value);
this.ValidateProperty("Name", value);
this._name = value;
this.RaisePropertyChanged("Name");
this.OnNameChanged();
}
}
}
/// <summary>
/// Computes a value from the key fields that uniquely identifies this entity instance.
/// </summary>
/// <returns>An object instance that uniquely identifies this entity instance.</returns>
public override object GetIdentity()
{
return this._name;
}
} 這個時候，如果我們在UI中繼續綁定這個實體類型，勢必會丢掉UI異常通知的行為，因為，顯然，我們不能跑到這個用戶端的代理類中throw new Exception("姓名不能為空"); ，那會在下一次代碼自動生成的時候被覆寫掉。
4：解決方案之建立映射
一種解決方案是我們的UI仍舊不綁定實體類型，而是為類型的屬性在ViewModel中建立一一映射的關系，如下：
public class MainPageVM : INotifyPropertyChanged
{
public MainPageVM()
{
user = new User();
serviceUser = new DomainServiceUser();
serviceUser.Load<User>(serviceUser.GetAUserQuery(), new Action<System.ServiceModel.DomainServices.Client.LoadOperation<User>>(this.GetAUserCallBack), null);
}
DomainServiceUser serviceUser;
User user;
void GetAUserCallBack(LoadOperation<User> arg)
{
user = (arg.Entities as IList<User>)[0];
Name = user.Name;
Age = user.Age;
}
public string Name
{
get { return user.Name; }
set
{
if (string.IsNullOrEmpty(value))
{
throw new Exception("姓名不能為空");
}
user.Name = value;
OnPropertyChanged("Name");
}
}
public int Age
{
get { return user.Age; }
set
{
if (value > 100)
{
throw new Exception("年齡必須小與100");
}
user.Age = value;
OnPropertyChanged("Age");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler pceh = PropertyChanged;
if (pceh != null)
{
pceh(this, new PropertyChangedEventArgs(propertyName));
}
}
} UI效果圖：
到此位置的源碼下載下傳為：
SilverlightApplication20110618.zip5：解決方案之使用ValidationSummary
使用ValidationSummary，需要我們引入程式集System.Windows.Controls.Data.Input，在UI前台，我們需要安置一個ValidationSummary：
接着，我們讓前台的ValidationSummary的Errors指派給VM。
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
ViewModel = new MainPageVM(this.vs.Errors);
}
public MainPageVM ViewModel
{
get
{
return (MainPageVM)this.DataContext;
}
set
{
this.DataContext = value;
}
}
private void btnSave_Click(object sender, RoutedEventArgs e)
{
}
} 我們還需要為UI綁定一些Command，以便在需要驗證輸入的時候，讓VM去判斷是否有錯誤發生。一旦有錯誤發生，則為Errors添加錯誤項。
public class MainPageVM : INotifyPropertyChanged
{
public MainPageVM(ObservableCollection<ValidationSummaryItem> errors)
{
m_errors = errors;
Click = new ActionCommand(this.OnClick);
serviceUser = new DomainServiceUser();
serviceUser.Load<User>(serviceUser.GetAUserQuery(), new Action<System.ServiceModel.DomainServices.Client.LoadOperation<User>>(this.GetAUserCallBack), null);
//serviceUser.Load<User>(serviceUser.GetAUserQuery(), LoadBehavior.RefreshCurrent, new Action<System.ServiceModel.DomainServices.Client.LoadOperation<User>>(this.GetAUserCallBack), null);
}
DomainServiceUser serviceUser;
User user;
ObservableCollection<ValidationSummaryItem> m_errors;
void GetAUserCallBack(LoadOperation<User> arg)
{
user = (arg.Entities as IList<User>)[0];
OnPropertyChanged("User");
}
public User User
{
get { return user; }
set
{
user = value;
OnPropertyChanged("User");
}
}
public ICommand Click { get; private set; }
public void OnClick(object arg)
{
m_errors.Clear();
if (User.Age > 100)
{
m_errors.Add(new ValidationSummaryItem("年齡不能大雨100"));
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler pceh = PropertyChanged;
if (pceh != null)
{
pceh(this, new PropertyChangedEventArgs(propertyName));
}
}
} 最後的運作結果為：
備注：要讓實體類在SL端支援EDIT，必須要讓DomainService針對該實體類支援開放GUID接口。如下：
[EnableClientAccess()]
public class DomainServiceUser : DomainService
{
[Query]
public IList<User> GetUsers()
{
return new List<User>()
{
new User() { Name = "huzhonghua", Age = 99 }
};
}
public User GetAUser()
{
return new User() { Name = "luminji", Age = 98 };
}
[Delete]
public void DeleteUser(User user)
{
throw new NotImplementedException();
}
[Insert]
public void InsertUser(User user)
{
throw new NotImplementedException();
}
[Update]
public void UpdateUser(User user)
{
throw new NotImplementedException();
}
} 本文源碼下載下傳：
SilverlightApplication2001061902.zip
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